Prior art methods of scanning two-dimensional scenes with a linear array camera are mostly dependent on either physically moving or translating the object to be scanned, physically moving or translating the entire camera and lens assembly; or optically redirecting the field of view of the camera and lens. by use of a single rotating scanning mirror; or an assembly of multiple mirrors in a rotating or translating configuration.
In the first two cases, translation of either the object or the camera and lens requires moving relatively large masses over relatively long distances. Mechanical realization of these systems results in expensive and slow mechanisms. For the third case, mirror rotation introduces at least two forms of scan error. One form of scan error is non-linearity due to converting rotational motion into linear motion. The second form of scan error is defocusing due to a change in optical path length either between the object and lens or the lens and the image plane.
In general, for any prior art scanning mirror or prism system, one of the two scan errors described occurs and must usually be corrected in some manner such as with the use of additional moving correcting mirrors or with limited utility f-theta lenses.
Several techniques are currently available for optically scanning an object or scene. However, all known methods suffer either from scan errors, or require movement of relatively large masses.
An object of the present invention is to produce a linear array camera having a linear optical scanning device that allows theoretically perfect linear translation of an image without defocus or other scan errors.
Another object of the present invention is to produce a linear array camera having a linear optical scanning device that may be constructed having a smaller size than equivalent performance devices of prior art, and allows theoretically perfect linear scanning of a large object field.
Another object of the present invention is to produce a linear array camera having a linear optical scanning device whereby adaptation for use with a large variety of lens types and focal lengths is simplified.
Still another object of the present invention is to produce a linear array camera having a linear optical scanning device whereby insertion of the linear optical scanning device into the image space between a lens and a camera or detector, when used with lenses with long back focal lengths, is simplified.